99 c1500 hi/lo headlight all on

Wondering if someone can splain to me where to install the diode in the under hood fusebox so when my hi beams are on, my low beams are on too... There are some very good diagrams on here showing different combinations, but none I see cover the 99 c1500 5.7... My fuses, relays and box is totally different..... Ideas please .....???